Basically, a passive radiator is a reactionary device as the name suggests. When a driver (such as a subwoofer) is mounted to a sealed speaker box (enclosure), the physical forward/back movement of the speaker affects the internal air pressure of the enclosure.
Three landforms created by wind are; sand dunes, yardangs (half-teardrop shaped formations hill sized, and deflation hollows (wind swept depressions.
3. Wavecut Platforms: horizontal benches of rock formed beneath the surf zone as a coast retreats by wave erosion. 4. Sea Stacks, natural arches First Effect of Marine Erosion intensity irregularity Then coast is smoothed through time